Cut two 8-inch circles from a clean grocery store bag or gallon size zip top back; set aside.
In a large bowl, combine the mass harina, 4 C warm water and salt. Mix and knead with your hands until the dough is smooth and homogenous. adding more water 1/4 C. at a time as needed. The dough should feel like Play-Doh: flexible, soft and smooth, not stiff. To test the dough, pinch off a bit and roll into a ball, and flatten between your palms. The dough should flatten easily, with few if any cracks forming around the edges. If deep U-shaped cracks form, add more water and test again.
Divide the dough into 2-oz. balls (about the size of golf balls), keeping them covered with a damp towel while you shape them.
Heat a large griddle over med heat. Use a tortilla press or the bottom of a wide, heavy pot to flatten the dough between the two pieces of plastic into a 6-inch tortilla of even thickness. Peel off the top piece of plastic, flip the tortilla over onto your hand and carefully peel away the other piece of plastic.
Slap tortilla onto the griddle to break any air bubbles and cook, flipping one, until the surface is brown in spots and appears dry, 1-2 minutes per side. While the first tortilla cooks, shape and begin cooking another. Continue shaping and cooking the remaining tortillas in the same manner. As they're done, wrap them in a slightly damp dish towel to keep warm.
Yield 35 tortillas
Tortilla filling suggestions: Shredded brisket with chipotle dressing, grilled tamarind chicken